diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c index c6695354b123..19b0cc5ea33f 100644 --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -95,6 +95,15 @@ static DEFINE_MUTEX(ashmem_mutex); static struct kmem_cache *ashmem_area_cachep __read_mostly; static struct kmem_cache *ashmem_range_cachep __read_mostly; +/* + * A separate lockdep class for the backing shmem inodes to resolve the lockdep + * warning about the race between kswapd taking fs_reclaim before inode_lock + * and write syscall taking inode_lock and then fs_reclaim. + * Note that such race is impossible because ashmem does not support write + * syscalls operating on the backing shmem. + */ +static struct lock_class_key backing_shmem_inode_class; + static inline unsigned long range_size(struct ashmem_range *range) { return range->pgend - range->pgstart + 1; @@ -396,6 +405,7 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) if (!asma->file) { char *name = ASHMEM_NAME_DEF; struct file *vmfile; + struct inode *inode; if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') name = asma->name; @@ -407,6 +417,8 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma) goto out; } vmfile->f_mode |= FMODE_LSEEK; + inode = file_inode(vmfile); + lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class); asma->file = vmfile; /* * override mmap operation of the vmfile so that it can't be